There should be no harm in adding an option to suppress the thing where it's not wanted.
Correct, that's what we're asking for.
The response to my proposal for such an option has been further argument the basic design is flawed and that anyone who thinks otherwise is insensitive to the needs of others.
I don't think that's the case at all, we're putting forward the reasons why we don't want the All item, or at least would like the option to choose when to have it. It gets problematic when someone else comes in and tries to tell us that other people would like it therefore the option to remove it should not be implemented!
I have actually found a use for it, but it's a very specific case. I'm experimenting with consolidating my theme park music and theme park videos into a top level category
outside and at the same level as the main Audio, Images and Video categories. The rationale being that I have a collection of theme park media and don't necessarily want to decide right at the beginning whether I want to listen to music, watch video or view photos. I just want to view media that I've got that relates to Alton Towers, for example.
So I have a top-level Theme Parks category that selects all media items with Genre = Theme Parks (this must be a common attribute across all media types for this to work). The next level down is an item of Media Type (which resolves to Audio, Images or Video) and the next level down is Park, so I can then select a particular media type and then a particular park as necessary, but there is also an "All Media Types" item which allows me to then drill down into a particular park and see all media for that park. The wording of this item, "All Media Types", makes complete sense in this case.
However, the subsequent "All" items below that, such as All Parks and All Albums, are meaningless and unnecessary and confuse the issue. I would never want to see a list of all photos across all parks.
This can be extended to other categories such as Holidays, where you might not be interested in particular media types all the time and want to see all videos and pictures relating to a particular vacation, in one folder. But you would never want to see all videos and pictures across all holidays in one list.
Another reason why the All Artist scenario doesn't work for many people is that it is a common requirement to sort all abums from an artist by year, not alphabetically. That's the way I have my collection organised. However, if I choose the All Artist item, it gives me a list of albums not filtered by a particular artist but the whole list of hundreds of albums, sorted by year. This is useless to me! If I wanted a list of my entire collection of albums I'd create another view that does not have an Artist level and that is sorted alphabetically.
So, in the first instance, a global option to turn the All item off would satisfy people who exclusively use a drill-down method.
Or you could further granularise it, as you've suggested, by putting the option on category or item level.
You mention the DLNA issue and want to know if the All item works differently on these devices, as though this matters. No, it doesn't work differently, it works in the same way. The issue is that DLNA devices themeselves, and indeed MC Theater View as a 10ft interface using a remote control, work differently from the main MC interface that uses a mouse, point-and-click, and scroll bars. Therefore the filtering facility which works well in Panes and split windows in the MC client doesn't translate so well to another interface and it's more important to be able to drill-down and minimise the number of items on the screen that you have to scroll through, and to be clear about exactly what it is you're seeing.
The All item doesn't stop you from using drill-down, it's just an extra item that is not needed, takes valuable space, is too prominent as the first item in a list, and confuses people who are used to drill-downs because of the interface they are using.